They stated a rule concerning peah: Anything that is a food, and is protected, and its growths are [nourished] from the ground, and its gathering is all at once, and one brings it in to last, is obligated in peah. Grain and legumes are covered by this rule.

And among trees: sumac, carobs, walnuts, almonds, grapevines, pomegranates, olives, and dates are obligated in peah.

He must always give as peah and it is exempt from tithes until he stacks.  And one may give away [produce] as hefker and it is exempt from tithes until he stacks.  And he may feed to an animal, to a beast, or to birds, and it is exempt from tithes until he stacks.  And he may take from the threshing floor and plant and it is exempt from tithes until he stacks; these are the words of R' Akiva.  [If] a Kohen or a Levi bought from the threshing floor, the tithes belong to them until it is stacked.  [If] one consecrates and redeems, he is obligated in tithes until the [Temple] clerk stacks.

The [following] divide [a field] for peah: a river, a canal, a private road and a public road, a public path or a private path that is in constant use during the hot season and the rainy season, fallow land, plowed land, and a different species.  [If] one harvests premature grain, he creates a division; [these are] the words of R' Meir. But the Sages say: It does not divide, unless he plowed.